Composite ceramic armor

ABSTRACT

A present variety of composite ceramic armor for protection against small arms fire consists of a dense ceramic plate bonded to a laminated fiberglass backing. the resistance of such armor to hits close to a free edge can be significantly improved by extending the backing over the edge of the plate and bonding it thereto, or by folding over the backing at the free edges and bonding it to itself.

[ Jan. 14, 1975 Primary Examiner-Stephen C. Bentley Attorney, Agent, orFirmCushman, Darby &

Cushman [57] ABSTRACT A present variety of composite ceramic armor forprotection against small arms fireconsists of a dense ceramic platebonded to a laminated fiberglass backing. the resistance of such armorto hits close to a free edge can be significantly improved by extendingthe backing over the edge of the plate and bonding it thereto, or byfolding over the backing at the free edges and bonding it to itself.

1 Claim, 5 Drawing Figures F4111 5/04 89/36 R, 36 A; 161/404,

Samuel H. Coes, 385 Daris Rd., Northboro, Mass. 01532 Mar. 14, 1969 [21]Appl. No.: 809,060

Related U.S. Application Data Continuation of Ser. No. 594,649, Nov. 14,1966, abandoned.

References Cited UNITED STATES PATENTS United States Patent Coes [COMPOSITE CERAMIC ARMOR [76] Inventor:

[22] Filed:

[51] Int. [58] Field of Search...........

COMPOSITE CERAMIC ARMOR This application is a continuation ofapplication Ser. No. 594,649 filed Nov. 14, 1966, now abandoned.

BACKGROUND OF INVENTION There has recently been developed a newarmorsystem for protection against high energy projectiles such as smallarms fire. Thisarmor consists of a hard high density ceramic platebacked by a bonded laminate of glass cloth bonded thereto. When sucharmor is struck on its ceramic face by a projectile of sufficiently highenergy, the ceramic face will fail and the energy delivered to thelaminated glass cloth backing will be dissipated in delamination of thebonded layers of cloth. When this occurs, persons or objects protectedbehind the armor will suffer no injury from the projectile.

However, when the projectile hits the armor within a few diameters ofthe projectile from a free edge of the armor, delamination, of thebacking occurs at the edge permitting particles of ceramic and theprojectile to escape behind the armor and thus personnel or equipmentbehind the armor, but in the path of such projectiles will not beprotected.

SUMMARY OF THE INVENTION THE DRAWINGS FIG. 1 shows a cross-section of aconventional type of ceramic composite armor which has been hit by aprojectile centrally of the plate and by a projectile near the edge ofthe plate;.

FIG. 2 shows a cross-section of a piece of ceramic armor according toone modification of the present invention;

FIG. 3 shows a cross-section of the armor of FIG. 2 which has sufferedan edge hit;

FIG. 4 shows a modification of the armor of the present invention incross section;

FIG. 5 shows the affect of an edge hit on the armor of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 it may be readilyseen that although the armor of conventional design consisting ofceramic plate and glass cloth laminate 11 is adequate to protect againstan impact such as at 12, an impact at 14 results in delamination andseparation of the glass cloth backing and essentially in failure of thearmor to perform its function. At 13, although the glass cloth laminateshave separated in an area at and around the point of impact, thesurrounding glass cloth remains bonded and effectively retains theintegrity of the composite plate. However, at 14 where the impact wasclose to an edge, delamination of the glass backing occurs at the edgeand frees the particles shattered from the ceramic plate and theprojectile itself to travel in paths behind the armor. r

FIGS. 2 and 3 show preferred embodiments of the present invention inwhich the type of failure shown at 15 in FIG. 1 is avoided.

The particular materials of which the ceramic plates 10 and are formedis of no moment insofar as the present invention is concerned.Typically, such materials may be high temperature fabricatedpolycrystalline alumina, silicon carbide or boron carbide. The backingelement 21 is formed ofa plurality of plies of glass cloth bondedtogether with a suitable resin such as a standard commercial catalyzedpolyester resin system. The backing 21 is bonded to the Ceramic 20 bymeans of any suitable commercial resin adhesive such as an epoxy resinadhesive. I

The particular dimensions of the ceramic plate and the backing dependupon the specific requirements for the armor and the particularmaterials which are employed in its manufacture. Merely for purposes ofillustration, the plates in FIGS. 1, 2 and 3 are three-fourths inch inoverall thickness with the ceramic plate being one-half inch thick andthe laminated glass fabric being one-fourth inch thick.

As can be seen by examination of FIG. 1, an area 13 in the glass clothll undergoes delamination around the site of the projectile impact onthe plate 10 shown in the drawing at 12. Where the impact occurs nearthe edge of the plate closer than that diameter of the area 13 to theedge, failure such as indicated at 15 will occur. Such failure isavoided in the embodiment of FIG. 2 by folding the backing element 21over the edge of the ceramic armor plate and bonding it thereto. Thissimple expedient entirely eliminates the spreading of the delaminatingforces occasioned by a hit such as at 14 to the extreme edge of theglass cloth laminate. FIG.

3 shows the effect of an edge hit at 24 on the plate 20. As shown, whilethe glass cloth laminate delaminates at 23, the separation of thelaminations does not extend all the way to the outer edge of the glasscloth.

FIG. 4 shows another embodiment of the invention wherein protectionagainst edge hits on the armor is improved. Instead of folding the glasscloth laminate backing down over the edge of the ceramic plate 30 as inthe embodiment of FIG. 2, the glass cloth is folded back over itself atthe free edges of the plate and securely bonded at and along the fold.As shown in FIG. 5, delamination of the backing occasioned by projectileimpact at 34 is limited in its spread due to the fold at 32 and nofailure of the backing occurs at its extreme edge.

The composite armor referred to herein may be of various shapes andsizes. It may generally be described as plate-like or planar. The platesare, in many instances, slightly curved, and so by planar or plane asused in the appended claims, we do not mean absolutely flat in themathematical sense.

I claim: i

l. A composite armor plate having a free edge, including a ceramic frontplate and a resin bonded glass fiber cloth laminated backing platebonded to said front plate, for protection against high energyprojectiles, the edge portion of said backing plate being bent at anangle of substantially folded back onto and bonded to itself, toreinforce said free edge against impact of high energy small armsprojectiles near said free edge.

UNITEDSTATES PA NT OFFICE I CERTIFICATE 01 CORRECTION Patent No.3,859,892 I hated Jan. 14, 975' Inv'entor(s) Samuel H. COES Itiscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

At paragraph [76] on the front page format, after "Samuel Hn Coes,"delete "385 Daris Rd." and insert --385 Davis Rd.a-

After paragraph [761 insert: --[-73] Assignee: Norton Company,Worcester, Massachusetts 01606-- At paragraph [57] entitled "Abstract",line 4, delete "the" and insert -The-- v Signed and sealec this 151: dayof July 1975.

(SZAL) Attest:

' C. MARSHALL DANN RUTH C. MASON Commissioner of Patents ArrestingOfficer and Trademarks UNITEDISTATES PATENT OFFICE A CERTIFICATE OFCORRECTION Patent No. 3,859,892 a Dated Jan. 14, 1975 i Inventor(s)Samuel H. COES It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

At paragraph [76] on the front page format, after "Samuel H, Coes,"delete "385 D'a 'r i-s Rd." and insert 385 Davis Rd.

After paragraph [76] insert: -[-73] Assignee: Norton Company, Worcester,Massachusetts 01606-- At paragraph [57] entitled "Abstract", line 4,delete "the" and insert -The- Signed and sealed this let day of July1975.

SEAL) Attest:

C. MARSHALL DANN RUTH C. I'IASOIZ Commissioner of Patents Arresting;Officer and Trademarks

1. A composite armor plate having a free edge, including a ceramic frontplate and a resin bonded glass fiber cloth laminated backing platebonded to said front plate, for protection against high energyprojectiles, the edge portion of said backing plate being bent at anangle of substantially 180*, folded back onto and bonded to itself, toreinforce said free edge against impact of high energy small armsprojectiles near said free edge.